A two stage pressure swing adsorption process to produce high purity oxygen from a feed air stream comprising steps (1) through (4) as described above is taught in the art. For example, U.S. Pat. No. 5,137,549 by Stanford et al. teaches such a process. The present invention is an improvement to Stanford whereby the effluent streams from steps (2) and (3) are used to regenerate the first stage adsorbent(s) in a specific regeneration scheme.